Lubricating oil



Patented July 31, 1945 LUBRICATING OIL Bert H. Lincoln, Ponca City,Okla., and Gordon D. Byrkit, Niagara Falls, N. Y., assignors, by mesneassignments, to The Lubri-Zol Development Corporation, Cleveland, Ohio,a corporation of Delaware No Drawing. Application October 7, 1942,Serial No. 461,128

' terious under conditions of thin film lubrication.

Claims.

This invention relates broadly to lubricants. More specifically, thisinvention relates to materials which, when added to lubricants, greatlyincrease their resistance to oxidation and formation of corrosiveproducts during use and increase their film strength and often improveother characteristics as well. This application is a continuation inpart of our copending application, Serial No. 323,959. filed March 14,1940, now Patent No. 2,302,703, granted November 24, 1942, which is acontinuation in part of Serial No. 231,362, filed September 23, 1938,and is related to our copend ing application Serial No. 419,990, filedNovember 21, 1941, which is also a continuation in part of Serial No,323,959.

Present-day mechanical devices require lubricating oils of high filmstrength, of high oiliness characteristics, and of low tendency tooxidize during use. It has been found that the presentday hydrocarbonlubricants of the very highest quality are deficient in these veryimportant characteristics. These three properties are of vitalimportance under conditions of thin film lubrication where the lubricanthas been squeezed from between the friction surfaces because of highpressure, slow speeds, and other causes. It is readily seen that theviscosity or the body of the lubricant plays no part in this type oflubrication and that the remaining film of oil must have a very highfilm strength and be of high oiliness value to prevent rupture of thefilm of the lubricant, which would cause seizure. The oil film must tendto keep the coefilclent of friction as low as possible. The oil mustresist oxidation'when these thin films are heated in the presence ofoxygen as they are in use.

Mechanical devices are being designed for higher pressure operation, andthe film strength of the best quality straight hydrocarbon lubricant hasbeen found to be too low. It will be obvious that an invention. whichprovides a means of improving the film strength of these lubricants isof great importance to the art of lubricant manufacture and to thedesigner and fabricator of mechanical devices.

The sludge is not a lubricant in any sense of the word, and the solubleacid is particularly corrosive to bearing metals such as cadmium-silver,copper-lead. and the like.

In starting idle mechanical equipment which is lubricated from a sump bypumping or circulating the lubricant, there is always a short period oftime in which the rubbing surfaces must operate under conditions of dryfriction if ordinary hydrocarbon lubricants are used. With dry friction,the wear on friction surfaces is extreme; and during cold weather whenthe lubricant is sluggish or during periods when the lubricating systemis not functioning properly for one reason or another, rubbing surfacesmay not only suffer considerable wear but may be damaged to the pointwhere they must be replaced. The product of our invention has a veryimportant property of reacting with the metal surfaces, penetrating oradsorbing on the ,metal surfaces, and leaving a film of lubricant withhigh oiliness character, which remains on the metal surface irrespectiveof the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which maybe easily discerned by the experienced operator or lubricating engineer.

When the hydrocarbon lubricants are diluted with unburned fuel or withother light hydrocarbons, the small degree of oiliness of the originalhydrocarbon lubricant is greatly decreased. We have found that theaddition of the products of our invention to hydrocarbon lubricants morethan compensates for the loss in oiliness and loadcarrying ability fromdilution.

It is well known that, in order to obtain lubricants which arepreeminently satisfactory from the standpoint of oxidation in use, it isnecessary to refine the oil thoroughly and then to add an inhibitor ofoxidation. The thorough refining may consist of more and heavier acidtreatments or solvent treating so as to remove a considerable part ofthe oil and leave only the most stable portion. Such drastic refining isnecessary in order to obtain stability with respect to sludge formationbut the oil is then subject to easy oxidation to form soluble acids andother corrosive results in blowby and hence loss or power, failure oflubrication, scratching, scoring, overheating, and eventuallyreplacement of parts. It is practically impossible to' refine a.lubricant in such a manner as to avoid all three of these difficulties,namely, sludge, soluble corrosive products, and lacquer. It isconsiderably more advantageous to add the materials of our invention andavoid these diii'culties by this method.

Many of these additive materials are efiective when added to poorlyrefined or even wholly unrefined lubricants. The addends may thus besubstituted in whole or in part for the usual refining processes.

In the prior art of applying these principles to the manufacture oilubricants, many diverse types of materials have been suggested to beadded to obtain improvement in various characteristics. It has beenfound that the addition of various organic esters of the oxygen andsulfur acids oi phosphorus frequently improves film strength,oxidation'resistance, non-corrosiveness, and other characteristics.Nitrogen compounds have beenv found to inhibit oxidation of oils. Ourmaterials combine both of these properties.

One object of our invention is to provide improved inhibitors ofoxidation and corrosion for addition to lubricants.

Another object of our invention is to provide film strength improvingaddition agents suitable,

for use in lubricants and especially in crackcase lubricants.

Qther and further objects of our invention will appear in the course ofthe following description.

In general, our invention comprises the addition to lubricating oils ofcertain organic phosphorus compounds characterized by the presence of anatom of phosphorus and an atom of nitrogen which are directly connectedto each other by a double bond, which is chemically combined in thecompound. The phosphorus may have a valence of 3 or 5. The phosphorus,in addition to being connected to an atom of nitrogen by means of twochemical bonds, may be directly connected to inorganic atoms such ashalogen, oxy en, or sulfur, directly connected to an organic radicalwhich may be aliphatic, carbocyclic, or heterocyclic, or connected to anorganic radical through an inorganic link which may be oxygen, sulfur,or nitrogen. The pentavalent phosphorus may be connected to variouscombinations of these radicals. The unsatisfied valence of the nitrogenwhich is connected to the phosphorus by a double bond may be connectedto an organic radical which may be aliphatic, carbocyclic, orheterocyclic in character or it may be connected to an inorganic radicalsuch as nitrogen which may, in turn, be connected to an organic radical,hydrogen, or another inorganic radical such as a halogen.

Compounds having a double bond between a phosphorus atomand nitrogenatom have outstanding antioxidant-properties. We do not know why this istrue, but the characteristic resides in these compounds. We believe thatthe antioxidant activity is a result of the augmented chemicalreactivity at the point of the double bond which is instrumental inreducing to an unusual degree the rate of oxidation :and the oxidationtendencies of the fuels and lubricants with which these compounds areblended. With a double bond between the nitrogen and phosphorus atoms,there is a likelihood that these may react with primary valence bonds inan oxidation reaction. thus, showing more chemical activity than whenall or the valences of the nitrogen and phosphorus atoms are satisfiedby primary valence bonds.

Reference may be made to the United States Patent No. 2,302,703, issuedNovember 24, 1942, on the application of Bert H. Lincoln and Gordon D.Byrkit, Serial No. 323,959, filed March 14, 1940, for informationrelative to the phosphorus-nitrogen compounds having a double valencebond between the nitrogen and phosphorus.

The halogen-bearing organic nitrogen compounds wherein the nitrogen andphosphorus are connected by a double bond are particularly eflectiveaddition agents for lubricating oils and fuels. These halogen-bearingcompounds, have the ability to produce the salutary eflfect oi. greatlyincreasing the film strength of the lubricant containing the compound asan addition agent as compared with the increase in film strength notedin a like blend in respect to proportion and kind of oil and additionagent of the organic phosphorus-nitrogen compounds described in PatentNo. 2,302,703 but which compound does not contain halogen. In additionto the marked increase in the film strength of oil containing ahalogenbearing addition agent as herein described, as compared to theunblended oil and nonhalogen containing oil, the coefficient of frictionof an oil into which has been incorporateda small quantity ofhalogen-containing organic phosphorusnitrogen compound is appreciablyless than the same oil containing a like amount of a halogenfree organicphosphorus-nitrogen compound. We believe this improvement is due to thepolarity of the compound containing the halogen. Our'theory is that theactive halogen atom or atoms chemically activate the organicphosphorus-nitrogen compound in such a manner that the halogen-bearingmolecules are induced to annex themselves on and near the surface of themetallic parts which they contact to form upon such metallic parts aprotective regimented film of multimolecular dimensions which isextraordinarily eiiective in resisting extreme pressures. This theory isin part substantiated by the fact that these additives enable alubricant to satisfactorily lubricate under nonfluid conditions andunder boundary lubrication conditions.

The halogen may be present in the compound in any one or in combinationsof its forms. One or more atoms of bromine, fluorine, iodine, chlorine,or combinations or these elements may be present in the compound. Theelement best suited for the practice 01' this invention is chlorinebecause it is more readily available and cheaper than the otherhalogens. The halogen may be in an organic radical attached to eitherthenitrogen or phosphorus or it may be directly attached to thephosphorus. The halogen in the compound may be residual halogenremaining in the product after preparation or it may be introducedsubsequent to the preparation or the organic phosphorus-nitrogencompound in a separate and distinct halogenation reaction or it may bepresent in the compound due to both causes.

In connection with this invention, the teaching in our United Statespatent Application Serial No. 419,990, filed November 21, 1941, shouldbe noted. There the beneficial eflect of combined sulfur is disclosed.We there disclose in' general that organic phosphorus-nitrogen compoundshaving ain the following outline.

gen and sulfur are particularly efi'ective addition agents because thelubricant exhibits great film strength, high oiliness, antioxidant, andanticorrosive properties.

Some of these materials which are suitable for use in accordance withour invention are shown oge 4. Phosphazobenzene chloride, GeHsNIPC] -5.Phosphazoxylene chloride, (CH;)CH;N:PC1

6. Phosphazochlorobenzene chloride ClCeH4N:PCl 7. Phosphazophenylbenzene bromi e, omcunmrm C. Anilides oi phosphazo-aromatics RN:P.NHR (Rand R are aromatic radicles at least one'oi which contains halogen).

8. Phosphazochlorobenzene chloroanilide,

CICH4N:P.NHCH4CI D. Oxyphosphazo-aryl anilides RNH .P:NR' (Rand R arearomatic radicals at least one of which contains halogen).

9. Oxyphosphazobenzochloroanilide, ClCiHiNEPOfNCQHt E.Trichlorophosphanils, RN2PO1:

10. Trichlorophosphanil, ciHtNzPCls 11. 'lrichlorophosphochloranil,CICBHINIPC]! F. 'Iriaryl phosphazines, R2CIN.NZPR'3 (R is aliphatic; Ris aromatic or aliphatic and halogen is in at least one of theradicals).

l2. Trl-o-chlorobenzyl dimethylphosphazine,

omboznNzrwmotniom G. Aryl phosphin-imines, RzPZNR' (R is aromatic; B.may be arematic or aliphatic, at least one of the radicals containshalogen).

l3. Tribenzyl o-chlorophenylphosphin-imine,

( 0 B 2)PZNctH4Cl I Any of these compounds or other members of theclasses in the above list or their derivatives or any other compoundwithin the limitations set forth in the generic description of thisinvention may. be used and such use is contemplated as within the scopeof this invention.

The compounds of group A of this invention may be made, for example, byreacting an amine which may or may not contain a halogen or an aminederivative which may or may not contain a halogen with (PSCla)thiophosphoryl chloride. The two hydrogen atoms on the amine nitrogenare removed with two chlorine atoms from the PSClz, thus giving thenitrogen phosphorus double bond. The compound will contain residualchlorine because an atom of chlorine will remain in the radicalrepresenting the thiophosphoryl chloride and may contain halogen becauseof the presence of an amount of chlorine in the amine or aminederivative. The organic radical attached to the amine or aminederivative may be either open chain or closed chain compounds with onlycarbon or with carbon and other elements, such as nitrogen, sulfur, andthe like. If the organic radical is a. closed chain of the aromatictype, various substitutents may be placed on the ring. For example,long-chain aliphatic radicals, like petroleum wax, may be substituted.Other organic radicals containing characteristic groups may also besubstituted; therefore amines of waxylated benzene, naphthalene,cyclohexane. and the like may be reacted with Chemically saturated andunsaturated aliphatic amines may be employed in making the product ofour invention. For example, alkyl amine or sulfurized or chlorinatedalkyl amine may be employed. Hexyl amine and cyclohexyl amine,chlorinated or brominated hexyl amine and cyclohexyl amine, when reactedwith PSCla, give products usable in our lnventio It is to be understoodthat in practicing our invention, oil-soluble halogen-containing phos-All and each of these are to be selected. Some 0! the compounds withinthe scope of the broad definition of the compounds of use in thepractice of this invention have only limited solubility in hydrocarbonoils. It is to be remembered, however, that, because of their greatemciency, extremely small amounts are often effective. Thus we may useas little as 0.001 per cent of some of these compounds, and it will beseen that a fairly insoluble material may dissolve to a sufllcientextent to be satisfactory for our purpose. While certain specificexamples of the broad class of halogen-nitrogenphosphorus compoundsgiven above are not at all oil-soluble, it should be noted that onlythose which are soluble to at least the extent of 0.001% arecontemplated for use.

In general, more than 0.001 per cent of our addition agents are used,and we may add one, two, or even five per cent or more.

Furthermore, it is well known that different types of oils havediil'erent capabilities of dissolving a given material. fore, we preferparafllnic lubricants, while for other purposes we prefer naphthenic ormixed base lubricants. Another method of obtaining a satisfactorymixture of addition agent with the hydrocarbon oil is the use of amutual solvent to bring the addend into solution. Alternatively,peptizing agents may be added to maintain the organo-phosphorus-nitrogencompound in permanent suspension.

Many of the more difiicultly soluble materials are rendered more solubleby the introduction of alkyl groups, particularly those containing fouror more carbon atoms. The isoamyl, octyl, lauryl, and octadecyl radicalsand radicals from paramn wax greatly increase the solubility of organiccompounds in oil. One or more of such groups may be introduced asrequired into the previously described compounds or their derivatives.

In the selection of a particular compound or compounds to be used as anaddition agent to the hydrocarbon oil consideration should be given tothe uses for which the blend is designed. Thus, if water is likely to bepresent during use, a phosphorus compound or combination of compounds isselected which is not affected by water. In general, we prefer to usecompounds having boiling points over 250 F. It is sometimes advantageousto. combine more than one of these compounds in a blend to obtainparticular properties. We accomplish this by mixing two or more of thesecompounds together and blending the mixture with the hydrocarbon oil orby blending one in the hydrocarbon oil, blending the second into thismixture, and so on until the composition is complete.

The various halogen-phosphorus-nitrogen compounds improve both the filmstrength, oxidation characteristics, and the sludging characteristics orthe hydrocarbon oil. For example, the sludging tendencies may bedecreased by as little as 0.001 per cent of ourhalogen-phosphorus-nitrogen compounds. The oxidation characteristics oflubricants are very important, and these are markedly improved by ourcompounds. The ability to reduce friction is another feature contributedto lubricants by our halogen-phosphorus-nitrogen compounds.

It may be desirable to include in one and the same blend d on ahydrocarbon oil, in addition to the-addends here described, otheraddends for specific purposes. Thus, we may add a pour p osen omp undsof the type described point depressor such as .a naphthalene-chic: in

For some purposes, there-.

condensation product and a viscosity index improver such as certainresins or polymerized hydrocarbons in addition to our halogen-containingorgano-phosphorus compounds. Furthermore, various metallic compounds maybe added to the blend without interfering with the action of ouringredients. Indeed, in some cases it is advantageous to combine withour organic halogenbearing phosphorus-nitrogen compounds in ahydrocarbon oil blend such materials as calcium dichlorostearate,chromium oleate, tin octadecyl phthalate, aluminum stearate, and othermetallic soaps.

Our addends are admirably adapted for use in lubricating oils of alltypes including those designed for use in automotive crankcases. Dieseloils, and any other oils of lubricating viscosity such as castor oil,cottonseed oil, lard oil, sperm oil, shale oil. Furthermore, our addendsar advantageously blended in gasoline and other petroleum fuelseithef'directiy or after being blended first in a lubricating oil andthen added to the fuel. Soap-thickened mineral oils of all types rangingfrom those showing only a slight increase in viscosity over that of themineral .oil alone to the semisolid and solid greases containing fiftyper cent or more of soap are amenable to treatment according to ourinvention. In making these greases, the usual soaps such as sodiumstearate, aluminum stearate, calcium soaps of beta fat and the like maybe used. Various other thickening ingredients or materials for otherpurposes may be added. These include yarn, hair, graphite, glycerol,water, lamp black, mica, zinc dust, litharge, and the like.

The following examples of blends of our addition agents are given asillustrations but not as limitations:

Example 1 Per cent Mid-Continent paraflln-base SAE 30 99.0

Sulfophosphasobenzene chloride 1.0 Example 2 Per cent Mid-Continentmixed base SAE 50 98.5

Aluminum naphthenate 1.0

Sulfophosphazomethylbenzoate chloride--- 1.5 Example 3 Per centMid-Continent mixed base SAE 50 99.0

Trichlorophosphanil 1.0 Example 4 Per cent Mid-Continent paraflin-baseSAE 20 99.2

Tri-o-chlor-benzyl dimethylphasphazine .8

Example 5 Per cent Mid-Continent paraffin-bas'e SAE 20Phosphazochlorobenzene chloride Example 6 In making a lubricatinggasoline, we blend 0.5 per cent of the product of Example 1 withgasoline. The product has the composition:

Per cent Gasoline 99.5 Oil .495 Sulfophosphasobenzene chloride .005

It is to be understood, however, that the hydrocarbon oil in the treatedfuels may be of a viscosity or from about 35 seconds at 100 F. S.S.U. to350 seconds or more and the amount of oil blended with thehalogen-phosphorus-nitrogen compound to form the fuel addend may varybetween 0 per cent and 99.5 per cent. In some cases the fuel may beprepared without adding any hydrocarbon oil. The quantity ofhalogen-sulphur-prosphorus-nitrogen compound in the final blended fuelmay vary from 0.0001 to 1.0 per cent or slightly more.

It will be understood that certain features and sub-combinations may beemployed without reference to other species or combinations. This iscontemplated by and is within the scope of our claims. It is furtherobvious that various changes may be made in details within the scope ofour claims without departing from the spirit of our invention. It istherefore to be understood that our invention is not to be limited tothe details described.

Having thus described our invention, we claim:

1. A lubricant comprising in combination a major proportion of oil oflubricating viscosity and a minor proportion of an oil-solublehalogencontaining phosphazine.

2. A lubricant comprising in combination a major proportion of oil oflubricating viscosity and a rrinor proportion of an oil-solublechlorine-con ainin phosphazine.

3. A lubricant comprising in combination a 'major proportion of oil oflubricating viscosity and a minor proportion of an oil-solublehalogencontaining phosphazo-aromatic anilide.

4. A lubricant comprising in combination a 'major proportion of oil oflubricating viscosity and a minor proportion of tri-o-chloro-benzyldimethylphosphazine.

5. A lubricant comprising in combination a major proportion of oil oflubricating viscosity and a minor proportion of an oil soluble halogencontaining organic phosphorus compound of the class consisting ofcompounds of the following types: R=NN=P--R and R'N=P--N-R where two ormore nitrogens are present in the molecule, at least one of which isconnected to phosphorus by a double bond.

BERT H. LINCOLN. GORDON D. BYRKIT.

